The present invention concerns a self-emptying centrifuge drum with at least one valve for releasing solids. The drum is actuated hydraulically by water introduced into a collecting channel through a fitting. The collecting channel rotates with the drum, and the fitting is stationary and has at least one outlet.
A drum of this type is known, from German 3 826 912 C1 for example. The water fitting extends in the form of an enclosed channel into the area radially inside the collecting channel. The spindle that rotates the drum extends through the same area. The inside diameter of the collecting channel is accordingly dictated by the diameter of the spindle and by the radial length of the water fitting in the vicinity of the collecting channel. The stationary fitting must also be far enough from the rotating collecting channel and from the rotating spindle. Since an enclosed channel takes up a lot of space radially with its wall and free cross-section, the inside diameter of the collecting channel must accordingly be longer. The greater the capacity of the collecting channel, however, the weaker the hydraulic pressure generated by the water flowing into the collecting channel. Attempts are accordingly made to keep the diameter of the collecting channel as short as possible.
Making the water fitting a double-walled ring surrounding the spindle in the vicinity of the collecting channel has also been proposed, in German OS 1 532 676 for instance. This makes it possible to decrease the radial length of the water fitting without altering the open cross-section that the water flows through. The same design allows several water outlets in the vicinity of the collecting channel, facilitating the introduction of water into the collecting channel. Water fittings of this type are complicated, however, and always require the collecting channel to be relatively wide. All double-walled water fittings, furthermore, entail the risk of constricting the flow with deposits of dirt or lime.